Color motion pictures are often made by shooting the action with a film camera, converting the images to digital form, computer processing the digital images, and then scanning the processed images back onto film for release. It would be advantageous to have a practical electronic color video camera that could directly shoot the action to obtain color video from which good quality color motion picture film could ultimately be produced, but this has not yet been commercially achieved on a significant scale. In copending U.S. patent applications Ser. Nos. 09/653,983 and 09/954,969, both assigned to the same assignee as the present application, there are disclosed various features that improve the practical viability of electronic film origination. The present invention relates to image sensing CCD's that can be employed in electronic cinema cameras, including, but not limited to, the type thereof that may be used for film origination.
In an electronic cinema camera a mechanical shutter is used so that the exposure time is about half the frame interval. This is to prevent too much motion blur for moving objects. A frame transfer CCD needs a shutter to shut the light off while the charges are being transferred from the sensing area to the storage area. This prevents vertical smear in the image. In a full frame CCD (as is used in digital still cameras) there is no storage area. The image is clocked out of the sensing area in the dark while the shutter is closed.
In the electronic cinema camera, the HDTV standard that is used is 1920×1080 pixels. A common CCD that is manufactured is 2048×2048 pixels. If half of these pixels are used for the storage area, then the sensing area would be 2048×1024. This is not quite the number of lines in the standard.
In a film motion picture camera, the viewfinder has a slightly larger field of view than the recorded frame. In that way the camera operator can see if something is about to get into the recorded image that shouldn't be there (like a mike boom, for example). It would be desirable for an electronic cinema camera to have a little overscan to provide this same function, and it is among the objects of the present invention to achieve this.
It is among the further objects of the invention to provide an electronic video camera and method, and a CCD sensor for same, that can operate with improved efficiency.